The barrier Israel is building along the West Bank has had an unforeseen effect: Palestinians are flooding back into Jerusalem to bolster their claim to the holy city.

Jerusalem — ISSA Natsheh watched warily from his West Bank suburb when Israel began building a concrete barrier along the fringes of Jerusalem four years ago.

As the partition slowly took shape, Natsheh grew increasingly worried that he would be cut off for good from the city of his birth. Powerless to stop the construction, Natsheh did what he could: He moved back into Jerusalem.

Two years after the move, Natsheh lives with a wife, three small daughters and a newborn son in a concrete-block shack on a trash-strewn hillside north of downtown. He built the structure without Israeli permission and has covered the front with a black tarp to disguise it so authorities won't tear it down.

Thousands of Palestinians like Natsheh, lured to the West Bank over the years by family ties, cheap property and fewer building regulations, are scrambling back into Jerusalem.

The unforeseen wave of migration has increased the Arab presence, bolstering a broader trend that has seen the Palestinian population grow to more than a third of Jerusalem's total. It is one sign of how the barrier is reshaping the holy city and further complicating any effort to settle competing claims to it.

Israel insists that the barrier is aimed at keeping out suicide bombers and that the strategy is working. Officials say it can be dismantled if there is peace.

"The fence is not political. It's not a border. It's only a security fence," said Nezah Mashiah, an official at Israel's Defense Ministry who oversees the project. A system of crossing points should ensure that people with a right to enter Jerusalem are not impeded, Mashiah said.

But Palestinians are skeptical.

For many, moving back into the city is an act of nationalism, aimed at countering what they view as an Israeli effort to reduce their numbers and undermine their aspirations to make East Jerusalem the capital of a future Palestinian state. For most others, even if they want nothing else to do with Israeli authorities, the purpose is access to jobs, healthcare, social security and other benefits Israel provides to Jerusalem residents.

By disrupting traditional commercial links to the West Bank, the barrier is transforming the region's economy while encouraging even more Palestinians to think about relocating.

The serpentine 90-mile section that roughly tracks Jerusalem's boundaries on three sides is part of a series of fences, concrete walls and patrol roads being built along the length of Israel's border with the West Bank, and sometimes deep into the Palestinian territory. The Jerusalem section, about two-thirds complete, is expected to be finished by early next year, Israeli officials say.

Palestinian officials have encouraged Jerusalem residents over the years to stay in the city to maintain their claim. But they have been largely silent, both publicly and privately, about the current migration, carefully avoiding any statements that would imply recognition of the barrier as a de facto border.

There are no reliable figures on how many Palestinians have moved back, but the number appears to be easily in the thousands. Israeli officials acknowledge that some movement has occurred. Because these Palestinians have a right to live in Jerusalem, the officials say, they have not tried to stop the migration, even though the influx could end up strengthening the Palestinian stake in the city.

In a report last year, the Jerusalem Institute for Israel Studies called the barrier "the most significant change that has taken place in the city since its reunification" after the 1967 Middle East War.

Family's trade-off

NATSHEH'S family planted roots in the West Bank suburb of Al Ram 34 years ago.

For much of the time since then, Jerusalem Palestinians have been relatively free to move between the city and the West Bank, regardless of the municipal borders drawn by Israel. Like Natsheh, 25,000 to 60,000 of the 240,000 Palestinians legally entitled to live in Jerusalem eventually took up residence in the West Bank, according to Israeli and Palestinian researchers.

In Al Ram, Natsheh had a 2,100-square-foot house, big enough for his two wives and all eight of his children.

He was tied closely to the Palestinian cause, and acknowledges that he once served as little more than an armed thug for Yasser Arafat's Fatah movement. He was twice imprisoned by the Israelis, once for 10 years after being caught in 1976 with an improvised car bomb and again in 1990, serving four years for arms dealing.

By moving back to Jerusalem, he is in effect opting for a future more closely tied to Israel than to the problem-ridden Palestinian territories. The reason, he said, is quality of life.

"I don't feel good about it," said Natsheh, 53. Somber and reflective, he puffed cut-rate cigarettes in a tattered chair on the stoop of his new home and appeared to still be trying to make peace with his decision.